Conventional trocars use an obturator with a sharp metal tip to penetrate a body cavity in surgical procedures. After each use the obturator must be sterilized and eventually the tip dulls and must be re-sharpened by machining. These obturators are expensive and adding to their effective cost is the cost of sharpening, sterilizing and the loss of use during those procedures. Some trocars including housing, handle, cannula and obturator are made to be disposable: they are made to be used once and discarded with no need for resharpening or sterilizing but their initial cost is quite high. Some trocar obturators are made with a removable metal tip so that tips of different cutting configurations can be used by simple removal and replacement of them from the obturator shaft. But these tips, too, are expensive and must be regularly sterilized and periodically re-sharpened.